Drip coffee makers have become popular in recent years. They operate by drip brewing coffee, then collecting the brewed coffee in a pot. The pot is usually built from a heat resistant material such as Pyrex. The pot sits on a hot plate or burner, which is used to heat coffee and maintain it at a drinkable temperature.
Unfortunately, the heat from a hot plate will cause evaporation from a coffee pot. As such a pot nears empty through evaporation, the coffee becomes overcooked, adversely affecting its taste. Pouring cups of coffee accelerates this. Additionally, should all moisture evaporate, the pot will burn.
Two general approaches have been tried to circumvent this problem. First, a spacer is used to separate the coffee pot from the hot plate with a blanket of air. The blanket of air acts to limit the temperature that the coffee can reach. This approach has the disadvantage of supplying too little heat when a pot is full, and too much heat when a pot is empty.
The second approach is to decrease the amount of heat being applied to a coffee pot by a hot plate, as the amount of liquid in the pot decreases. This decrease in temperature usually is based on a decrease in the weight of the pot. The problem with most of these inventions is their complexity. Invariably there are multiple moving parts.
The current invention provides a simple solution to the problem. A blanket of air can be left between a coffee pot and a hot plate or burner. The distance between the pot and plate increases as the weight of the pot decreases due to evaporation or whatever, resulting in less heat being applied to the pot by the hot plate.
The invention is significantly simpler than the other inventions that use a decrease in weight to raise a coffee pot off of a hot plate. Indeed, it is possible to construct each of the preferred embodiments disclosed herein from a single piece of metal. This simplicity has advantages in cost of manufacturing and in maintenance.
As can be seen, whereas the invention has its most immediate application when used with a drip coffee maker, it has applicability whenever a liquid (or maybe even a solid) is heated by either a hot plate or a burner.
The following is the prior art known to the inventor that might be pertinent to the patent examiner in the examination of this examination.
U.S. Pat. No. 4,158,125 by Jones describes the use of a coil spring to lift a pot off of a hot plate to reduce the heat applied to the pot as the weight of the pot decreases.
U.S. Pat. No. 4,164,645 by Dogliotti describes a device for quickly heating drinks. A Whetstone Bridge is used to set the desired temperature of the liquid being heated.
U.S. Pat. No. 4,170,931 by Fajans describes a spacer that limits direct heating of water during brewing in a percolator on a hot plate to water in a pumping assembly of the percolator.
U.S. Pat. No. 4,206,341 by Leuschner et al. describes a device that uses the rotation of a cam to move a container away from a hot plate in order to reduce the heat applied to the container.
U.S. Pat. No. 4,406,942 by Lo Conti describes a spacer consisting of a 1/16" steel wire used to control heating over a hot plate.
U.S. Pat. No. 4,772,777 by Weller et al. describes a temperature sensitive apparatus that lifts a container off of a hot plate to reduce the heat applied to the container.
U.S. Pat. No. 4,896,022 by Schroeder et al. describes a plastic carafe heated on a standard hot plate by interposing a blanket of air heated by convection. The temperature is regulated by holes.
U.S. Pat. No. 4,927,997 by Bailey describes a heat transfer pad removably mounted on a burner element.
U.S. Pat. No. 4,994,649 by Roland et al. describes a spacer ring to move a pot a constant distance from a hot plate.